The present invention relates to the testing of arrays of detectors, and specifically, the testing of mosaic arrays of infrared detectors.
Electrical contact to the inner detector elements of infrared mosaic arrays is normally made through individual columns of indium that are fused into the storage wells of silicon charge-coupled-device multiplexer integrated circuits. Current practice is to test all individual elements of the detector arrays following permanent fusion with the silicon integrated circuit.
To date, no procedure or apparatus has been known to test all the individual detector elements of the detector array prior to its fusion with the semiconductor circuit. Probing each individual detector element of the detector array is generally not feasible with today's detector arrays. Current infrared detector arrays have a large number of individual detector elements in an extremely small area. If some significant number of elements of either the detector array or the semiconductor circuit are defective, the complete detector device then is not usable and must be discarded. The exact number of defective elements that may be tolerated depends upon the application to which the detector array is to be put, and will vary accordingly.
The yield (percentage of acceptable devices) for the combined structure is the product of the yield for the detector array and the yield for the semiconductor integrated circuit. For example, if the yield of the detector arrays is 10% and the silicon IC is 20%, the overall yield is only 2%. Thus, the yield of completed devices has been quite small, causing the completed detector structures to be quite expensive.